In international law, naval ships are required to fly their national flag or ensign ("colours") before commencing hostilities. If the colours are taken down during battle, it signifies surrender. Hence, particularly defiant combatants will "nail the colours to the mast" to signal a refusal to surrender.
Hoisting a white flag signifies a request for a truce, not an indication of surrender as is commonly believed.
Gruel is a thin watery porridge made from oats, wheat or rice. It was a staple food for the poor, with a history going back to ancient Greece. It is commonly associated with workhouses and was made famous by Charles Dickens' classic Oliver Twist, in which Oliver memorably dares to ask for more. Although it has some nutritional value, gruel is often thin, grey and unappetising, and has been well represented in fiction as the food of mean, miserly characters.
3 or 4 tablespoons oatmeal
1 pint cold water
pinch of salt
Mix the oatmeal with a splash of water in a pan to make a paste. Add the rest of the water, stir well and bring to the boil. Cook on a gentle boil for about ten minutes. Add salt to taste.
Hay-making was a big task, and often all members of a household would be asked to lend a hand. Time was of the essence, as it was essential to get the hay in before the next rain. Hay-making could become quite an event.
Gypsies was the name given to Romani travellers. Having no permanent home, they wandered from place to place in travelling caravans. The first gypsies are believed to have come from Egypt, hence the name gypsy, and this would explain their darker skin and hair. Heathcliff, with his brooding dark looks and general air of scruffiness would have fit the prevailing idea of what a gypsy looked like; they were perceived to be unclean and untrustworthy. Groups of gypsies can still be found in the UK today, although the term now covers nomadic travellers of all nationalities, not just the Romani.
Joseph's religious fervour makes an appearance time and time again in Wuthering Heights. Brontë writes of it in an almost scornful manner, her contempt for his piety obvious. When the book was written, religion was still an important part of everyday life for most people in England, and growing up with a curate for a father, Emily would very likely have been exposed to people like Joseph.